Related papers: A Dark Hydrogen Cloud in the Virgo Cluster
An extended HI cloud (VIRGOHI 21) with an HI mass of $\sim10^8$ M$_{\odot}$ and no apparent optical counterpart was recently discovered in the Virgo cluster. In order to understand the origin of physical properties of apparently isolated HI…
Many observations indicate that dark matter dominates the extra-galactic Universe, yet no totally dark structure of galactic proportions has ever been convincingly identified. Previously we have suggested that VIRGOHI 21, a 21-cm source we…
Dark Matter supposedly dominates the extragalactic, yet no totally dark structure of galactic proportions has ever been convincingly identified. Earlier (Minchin et al. 2005) we suggested that VIRGOHI 21, a 21-cm source we found in the…
We have observed six `dark' neutral hydrogen (HI) clouds discovered in the Virgo cluster by the Arecibo Galaxy Environment Survey (AGES) with the Karl G. Jansky Very Large Array (VLA), giving higher angular and velocity resolution than the…
Because of its proximity and richness on late-type galaxies, the Virgo cluster has been the subject of numerous studies exploring the effect of the intracluster environment on galaxy evolution. First discovered nearly three decades ago by…
Very sensitive 21cm HI measurements have been made at several locations around the Local Group galaxy M31 using the Green Bank Telescope (GBT) at an angular resolution of 9.1', with a 5$\sigma$ detection level of $\rm{N_{HI} = 3.9 \times…
We report the discovery by the Arecibo Legacy Fast ALFA (ALFALFA) survey of eight HI features not coincident with stellar counterparts in the Virgo Cluster region. All of the HI clouds have cz < 3000 km/s and, if at the Virgo distance, HI…
We present observations of an HI cloud complex most likely located in the Virgo galaxy cluster, first reported by Kent et al. (2007). The complex consists of five clouds, detected in the data set of the ALFALFA extragalactic HI survey at…
We report the discovery of a large HI cloud in the central regions of the Virgo cluster. It is 110 x 25 kpc in size and contains 3.4 x 10^8 Msol of HI. The morphology and kinematics of this cloud strongly suggest that it consists of HI…
Most detected neutral atomic hydrogen (HI) at low redshift is associated with optically bright galaxies. However, a handful of HI clouds are known which appear to be optically dark and have no nearby potential progenitor galaxies, making…
We report the results of an HI blind survey of 80deg^2 of the Virgo cluster, based on the 08deg < delta < 16 deg strip of ALFALFA, the Arecibo Legacy Fast ALFA Survey. 187 HI sources of high significance are found providing a complete…
The Arecibo Legacy Fast ALFA survey is in the process of yielding a complete HI dataset of the Virgo Cluster and its environs (Giovanelli et al. 2007, Kent et al., in preparation). Assuming a distance to Virgo of 16.7 Mpc, the minimum…
We present 21 cm observations of a 10 $\times$ 2 degree region in the Virgo cluster, obtained as part of the Arecibo Galaxy Environment Survey. 289 sources are detected over the full redshift range (-2,000 $<$ $v$$_{hel}$ $<$ + 20,000 km/s)…
Aperture synthesis observations of two HI cloud complexes located in the periphery of the Virgo galaxy cluster are presented. These low HI-mass clouds ($M_{HI}<$ 10$^{9}$) are seen projected on the M region of the western Virgo cluster,…
Ultra diffuse galaxies (UDGs) have the sizes of giant galaxies but the luminosities of dwarfs. A key to understanding their origins comes from their total masses, but their low surface brightnesses ($\mu(V) \geq$ 25.0) generally prohibit…
High sensitivity (rms noise $\sim 0.5$ mJy) 21-cm HI line observations were made of 33 galaxies in the Virgo cluster, using the refurbished Arecibo telescope, which resulted in the detection of 12 objects. These data, combined with the…
High speed collisions, although current in clusters of galaxies, have long been neglected, as they are believed to cause little damages to galaxies, except when they are repeated, a process called harassment. In fact, they are able to…
We present 21 cm observations of a 5 x degree region in the Virgo cluster, obtained as part of the Arecibo Galaxy Environment Survey. 13 cluster members are detected, together with 36 objects in the background. We compare and contrast the…
Green Bank Telescope (GBT) 21cm observations have revealed a faint, yet extensive HI cloud population surrounding the Andromeda Galaxy (M31). The newfound objects are likely analogs to the high-velocity HI clouds (HVCs) seen around the…
We have observed the NGC 2403 group of galaxies using the Robert C. Byrd Green Bank Telescope (GBT) in a search for faint, extended neutral hydrogen clouds similar to the clouds found around the M81/M82 group, which is located approximately…